Preheat the Oven: Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking soda, baking powder, and salt. Set aside.

Cream Butter and Sugars: In a large mixing bowl, beat the softened butter, brown sugar, and granulated sugar together until light and fluffy, about 2-3 minutes.

Add Eggs and Vanilla: Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract until combined.

Combine Wet and Dry Ingredients: Gradually add the dry ingredient mixture to the wet ingredients, mixing just until combined. If using oats, fold them in at this stage.

Add the Candy and Chocolate Chips: Gently fold in the mixed Halloween candies and chocolate chips until evenly distributed throughout the dough.

Scoop the Dough: Use a cookie scoop or tablespoon to drop dough onto the prepared baking sheets, spacing them about 2 inches apart.

Bake: Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden but the centers are still soft.

Cool and Serve: Remove from the oven and let the cookies cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.

Enjoy: Serve these festive cookies warm or at room temperature, and enjoy the overload of Halloween flavors!